考虑温度和地层流体渗入共同影响的深水水下井筒环空带压产生机理及预测方法研究

A faultless subsea wellbore is the foundation of the safety and efficient exploitation of deep-water oil and gas. However, the issue of the SCP presents a serious challenge to the integrity of subsea wellbore, which is more prominent in well testing and production processes. Therefore, this project will take the subsea wellbore as the research object, and aim to discuss the mechanism and prediction method of the SCP in deep-water subsea wellbore during well testing and production with consideration of the combined action of temperature and fluid infiltration. The main research contents include: calculation and analysis of the temperature field of the whole deep-water wellbore in well testing and production, modeling and iterative solving of the SCP in deep-water subsea wellbore, prediction analysis of the allowable maximum value of the SCP, and conducting laboratory simulation experiments of the SCP. Finally, the mechanism of the SCP under the combined action of temperature and fluid percolation will be revealed, and a prediction method with complicated multi-variable parameters will be established according to the specific operating condition, physical property of the annular liquid, infiltration of the formation fluid, and the wellbore structure. The successful implementation of this project can provide foundation for effectively solving the SCP and improving the safety of deep-water oil and gas exploitation.

完整的水下井筒，是确保海洋深水油气安全高效开发的基础。然而，环空带压的存在，对深水水下井筒的完整性提出了严峻的挑战，且在测试及生产过程中更为突出。为此，本项目以深水水下井筒为研究对象，考虑温度和地层流体渗入的共同影响，探讨深水井测试及生产过程中水下井筒环空带压的产生机理与预测方法。具体内容包括：深水井测试及生产过程全井段井筒温度场分布规律计算与分析；深水水下井筒环空带压力学建模与迭代求解；深水水下井筒环空带压允许极值预测分析；深水水下井筒环空带压室内模拟实验研究。最后，揭示温度与地层流体渗入共同影响下的深水水下井筒环空带压产生机理，并建立基于作业工况、地层流体渗入、环空液体物性参数、井身结构等多因素影响的深水水下井筒环空带压预测方法。本项目的成功实施可为有效解决深水水下井筒环空带压难题和提高深水油气开发的安全性奠定基础。

环空带压精确预测与安全控制对于确保水下井筒完整性具有重要意义。本项目经攻关研究形成了以下成果及认识：（1）突破现有研究忽略套管环空液体轴向热交换的局限，建立了深水井测试及生产过程全井段井筒温度场分布规律预测方法，进一步提升了全井段井筒温度分布的预测精度；（2）建立了考虑温度和地层流体渗入共同影响下的深水水下井筒环空带压力学模型，弥补现有模型忽略地层流体渗入影响因素的缺陷，更为科学地揭示了水下井筒环空带压的产生机理；（3）根据所建环空带压力学模型，给出了深水水下井筒环空带压允许极值；（4）建立了基于理论分析和室内模拟实验相结合的深水水下井筒环空带压预测方法。共发表高水平论文11篇（SCI/EI收录9篇），申请发明专利2件，登记软件著作权2项，获省部级特等奖1项；全面完成了项目计划书规定的研究内容及考核指标。本项目成果可为研发新型水下井筒环空带压预防技术提供理论依据，对于确保海洋深水油气资源安全高效开发具有重要意义。